Oil Pressure

[mitchellp]

HI,
I have a 1989 Carver with Crusader 454 7.4 engines. The oil pressure gauge on one engine is not working. My first thought was the pressure sender, replaced that - did not fix it. It has dual stations, so I am pretty confident both gauges are not broken. Not sure what my next step might be.

Suggestions please.

Thanks
Mitch

[RobGunn]

Just to be safe until you find a fix for both stations. You can always install a mechanical gage directly on the engine just to see what the engine is truly doing.

[Sgodfrey]

This helped me …

https://www.cruisersforum.com/forums/f1 ... g-645.html

[km1125]

If you so install a mechanical gage on the engine, you should install a valve before it and only turn it on when you need to check. There have been several reports (one just recently) of the gages developing a leak which makes for a messy compartment if you don't find it quickly.

The first thing to do would be to check the wire from the sender to the engine harness connector. You should be able to find a pin-out for the harness connector and can open that up and inspect the connectors for any corrosion. Then ohm out the connection from the correct pin back to the sender. If that proves OK, then you can ohm from the "boat-side" of that same harness connection up to the gages. There is probably a "Y" connection under the lower helm that splits the engine harness so it can also feed the upper helm. Since both your upper station and lower station seem to have the same issue, then it should be isolated to the input connections on that "Y" harness or somewhere back towards the engine.

[Midnightsun]

Buy a cheap tester on Amazon to confirm you do have pressure. Once verified put sender back in place. assuming you do read pressure try disconnecting the wire at the gauge and then try grounding it to see if the gauge pegs. Verify there is 12v and ground with a volt meter at the gauge. The wire labeled "S" will be the one that goes to the sender and the one you want to ground or disconnect when verifying functionality of the gauge. Reason I say to do both is some senders work with ground and other without. If they do not peg then the gauges are bad, if they do peg wiring or sender is bad. To confirm a bad sender after a positive peg test, disconnect wire at sender and use the same method you used to peg the gauges at the gauge.

https://www.amazon.com/ABN-Engine-Pressure-Transmission-Diagnostic/dp/B0778XD4JT/ref=sr_1_4?crid=10S4HYU732YCT&keywords=oil+pressure+tester&qid=1659359451&sprefix=oil+pressur+tester%2Caps%2C80&sr=8-4

[km1125]

You could also just swap one of the "known good" gauges with one of the non-working ones to rule out a gauge issue.